Question 6:
Diagram 6.1(a) and 6.1(b) show a response of a flower towards light.
(a)(i) State the type of the response. [1 mark]
(ii) A gardener has moved the flower in Diagram 6.1(a) into a dark cupboard. Explain how the response of flower petals at 12.30 p.m. on the next day. [2 marks]
(b) Diagram 6.2 shows an experiment to study the effects of phytohormone on the growth of coleoptile at the shoot tip.
(i) Draw the observation of growth response that happened after two days on the space provided in Diagram 6.2. [1 mark]
(ii) State the hormone involved in the response. [1 mark]
(iii) Diagram 6.3 shows a graph of the effect of hormone concentration stated in 6(b)(ii) towards the growth of shoot and root.
Explain the effects of the hormone concentration towards the growth of shoot and root at concentration Z. [2 marks]
(c) In tissue culture technique, cytokinin hormone is added into the culture medium. State why the cytokinin hormone is added into the culture medium. [1 mark]
Answer:
(a)(i) Photonasty / Nastic response
(a)(ii)
P1: Flower petals are closed / does not bloom
P2: (Dark cupboard) no/lack of light
(b)(i)
(b)(ii) Auxin
(b)(iii)
P1: Shoot elongation is higher while root elongation is low
P2: (In Z ,) auxin stimulates cell elongation in shoots / the rate of cell elongation in shoots is high
P3: (In Z ,) auxin inhibits cell elongation in roots / the rate of cell elongation in roots is low
(c)
P1: Stimulates cell division/elongation
P2: Stimulates the formation of plant organs such as roots/stems
Diagram 6.1(a) and 6.1(b) show a response of a flower towards light.
(a)(i) State the type of the response. [1 mark]
(ii) A gardener has moved the flower in Diagram 6.1(a) into a dark cupboard. Explain how the response of flower petals at 12.30 p.m. on the next day. [2 marks]
(b) Diagram 6.2 shows an experiment to study the effects of phytohormone on the growth of coleoptile at the shoot tip.
(i) Draw the observation of growth response that happened after two days on the space provided in Diagram 6.2. [1 mark]
(ii) State the hormone involved in the response. [1 mark]
(iii) Diagram 6.3 shows a graph of the effect of hormone concentration stated in 6(b)(ii) towards the growth of shoot and root.
Explain the effects of the hormone concentration towards the growth of shoot and root at concentration Z. [2 marks](c) In tissue culture technique, cytokinin hormone is added into the culture medium. State why the cytokinin hormone is added into the culture medium. [1 mark]
Answer:
(a)(i) Photonasty / Nastic response
(a)(ii)
P1: Flower petals are closed / does not bloom
P2: (Dark cupboard) no/lack of light
(b)(i)
(b)(ii) Auxin
(b)(iii)
P1: Shoot elongation is higher while root elongation is low
P2: (In Z ,) auxin stimulates cell elongation in shoots / the rate of cell elongation in shoots is high
P3: (In Z ,) auxin inhibits cell elongation in roots / the rate of cell elongation in roots is low
(c)
P1: Stimulates cell division/elongation
P2: Stimulates the formation of plant organs such as roots/stems